Ensure a function is only called once
When called multiple times it will return the return value from the first call.
Unlike the module once, this one isn't naughty and extending Function.prototype
.
$ npm install onetime
const onetime = require('onetime'); let i = 0; const foo = onetime(() => ++i); foo(); //=> 0 foo(); //=> 0 foo(); //=> 0 onetime.callCount(foo); //=> 3
const onetime = require('onetime'); const foo = onetime(() => {}, {throw: true}); foo(); foo(); //=> Error: Function `foo` can only be called once
Returns a function that only calls fn
once.
Type: Function
Function that should only be called once.
Type: Object
Type: boolean
Default: false
Throw an error when called more than once.
Returns a number representing how many times fn
has been called.
Note: It throws an error if you pass in a function that is not wrapped by onetime
.
const foo = onetime(() => {}); foo(); foo(); foo(); console.log(onetime.callCount(foo)); //=> 3
Type: Function
Function to get call count from.
MIT © Sindre Sorhus